A Practical Guide to Building an Agent Harness From Scratch
omarsar0 · x · 2026-09-15
Elvis (omarsar0) shares how to build an agent harness from scratch. He recommends implementing one yourself in TypeScript or Python, starting from the ReAct paper — you can even prompt an agent to read the paper and produce a minimal implementation you can inspect.
Target architecture with three modules:
- LLM module: handles all inference, ideally supporting multiple models (he used OpenRouter when starting); the system prompt can be embedded or kept separate for deeper context-engineering experiments.
- Tools module: recommended to build them as… (truncated).
- Plus the remaining execution/orchestration parts.
Related event: Build your own agent harness from scratch: a minimal three-module guide(3 posts)→
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